The mechanisms of intestinal absorption of the important micronutrients alpha-tocopherol,vitamin D-3, and vitamin K-2, will be explored in vivo. The influence of fatty acids, bile salts, perfusate pH, and the thickness of the unstirred water layer on the absorption of these micronutrients will be investigated. Studies will also be conducted with chronic lymph and bile fistula rats. The appearance rate of these micronutrients in lymphatic and biliary drainage will be studied under conditions of variable bile salt concentrations, variations in infusate pH, the addition of short, medium, and long chain saturated fatty acids, and the concomitant presence of polyunsaturated fatty acids. We are also planning to investigate the possibility of circadian rhythmicity in the absorption in vivo of the lipid soluble vitamins as well as the influence of endogenous, biliary, and pancreatic secretions on their absorption in vivo. This information whould be helpful in the clinical management and understanding of absorption disorders seen in patients with common bile duct obstruction or pancreatic insufficiency. BIBLIOGRAPHIC REFERENCES: Hollander D: Mechanism and site of small intestinal uptake of vitamin D-3 in pharmacological concentrations. Amer J Clin Nutr 29:970-975, 1976. Hollander D, E Rim, and KS Muralidhara: Vitamin K-1 intestinal absorption in vivo. Influence of luminal contents on transport. Amer J Physiol 232(1):E69-E74, 1977.